package org.apache.lucene.search.spans;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;

import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Set;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.Query;
import org.apache.lucene.util.ToStringUtils;

/** Matches spans which are near one another.  One can specify <i>slop</i>, the
 * maximum number of intervening unmatched positions, as well as whether
 * matches are required to be in-order. */
public class SpanNearQuery extends SpanQuery implements Cloneable {
    protected List<SpanQuery> clauses;
    protected int slop;
    protected boolean inOrder;

    protected String field;
    private boolean collectPayloads;

    /** Construct a SpanNearQuery.  Matches spans matching a span from each
     * clause, with up to <code>slop</code> total unmatched positions between
     * them.  * When <code>inOrder</code> is true, the spans from each clause
     * must be * ordered as in <code>clauses</code>.
     * @param clauses the clauses to find near each other
     * @param slop The slop value
     * @param inOrder true if order is important
     * */
    public SpanNearQuery(SpanQuery[] clauses, int slop, boolean inOrder) {
        this(clauses, slop, inOrder, true);
    }

    public SpanNearQuery(SpanQuery[] clauses, int slop, boolean inOrder, boolean collectPayloads) {

        // copy clauses array into an ArrayList
        this.clauses = new ArrayList<SpanQuery>(clauses.length);
        for (int i = 0; i < clauses.length; i++) {
            SpanQuery clause = clauses[i];
            if (i == 0) { // check field
                field = clause.getField();
            } else if (!clause.getField().equals(field)) {
                throw new IllegalArgumentException("Clauses must have same field.");
            }
            this.clauses.add(clause);
        }
        this.collectPayloads = collectPayloads;
        this.slop = slop;
        this.inOrder = inOrder;
    }

    /** Return the clauses whose spans are matched. */
    public SpanQuery[] getClauses() {
        return clauses.toArray(new SpanQuery[clauses.size()]);
    }

    /** Return the maximum number of intervening unmatched positions permitted.*/
    public int getSlop() {
        return slop;
    }

    /** Return true if matches are required to be in-order.*/
    public boolean isInOrder() {
        return inOrder;
    }

    @Override
    public String getField() {
        return field;
    }

    @Override
    public void extractTerms(Set<Term> terms) {
        for (final SpanQuery clause : clauses) {
            clause.extractTerms(terms);
        }
    }

    @Override
    public String toString(String field) {
        StringBuilder buffer = new StringBuilder();
        buffer.append("spanNear([");
        Iterator<SpanQuery> i = clauses.iterator();
        while (i.hasNext()) {
            SpanQuery clause = i.next();
            buffer.append(clause.toString(field));
            if (i.hasNext()) {
                buffer.append(", ");
            }
        }
        buffer.append("], ");
        buffer.append(slop);
        buffer.append(", ");
        buffer.append(inOrder);
        buffer.append(")");
        buffer.append(ToStringUtils.boost(getBoost()));
        return buffer.toString();
    }

    @Override
    public Spans getSpans(final IndexReader reader) throws IOException {
        if (clauses.size() == 0) // optimize 0-clause case
            return new SpanOrQuery(getClauses()).getSpans(reader);

        if (clauses.size() == 1) // optimize 1-clause case
            return clauses.get(0).getSpans(reader);

        return inOrder ? (Spans) new NearSpansOrdered(this, reader, collectPayloads) : (Spans) new NearSpansUnordered(this, reader);
    }

    @Override
    public Query rewrite(IndexReader reader) throws IOException {
        SpanNearQuery clone = null;
        for (int i = 0; i < clauses.size(); i++) {
            SpanQuery c = clauses.get(i);
            SpanQuery query = (SpanQuery) c.rewrite(reader);
            if (query != c) { // clause rewrote: must clone
                if (clone == null)
                    clone = (SpanNearQuery) this.clone();
                clone.clauses.set(i, query);
            }
        }
        if (clone != null) {
            return clone; // some clauses rewrote
        } else {
            return this; // no clauses rewrote
        }
    }

    @Override
    public Object clone() {
        int sz = clauses.size();
        SpanQuery[] newClauses = new SpanQuery[sz];

        for (int i = 0; i < sz; i++) {
            newClauses[i] = (SpanQuery) clauses.get(i).clone();
        }
        SpanNearQuery spanNearQuery = new SpanNearQuery(newClauses, slop, inOrder);
        spanNearQuery.setBoost(getBoost());
        return spanNearQuery;
    }

    /** Returns true iff <code>o</code> is equal to this. */
    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (!(o instanceof SpanNearQuery))
            return false;

        final SpanNearQuery spanNearQuery = (SpanNearQuery) o;

        if (inOrder != spanNearQuery.inOrder)
            return false;
        if (slop != spanNearQuery.slop)
            return false;
        if (!clauses.equals(spanNearQuery.clauses))
            return false;

        return getBoost() == spanNearQuery.getBoost();
    }

    @Override
    public int hashCode() {
        int result;
        result = clauses.hashCode();
        // Mix bits before folding in things like boost, since it could cancel the
        // last element of clauses.  This particular mix also serves to
        // differentiate SpanNearQuery hashcodes from others.
        result ^= (result << 14) | (result >>> 19); // reversible
        result += Float.floatToRawIntBits(getBoost());
        result += slop;
        result ^= (inOrder ? 0x99AFD3BD : 0);
        return result;
    }
}
